Method and system for imaging and modeling dental structures

ABSTRACT

Systems and methods optically image a dental structure within an oral cavity by: directing air at a tooth-gum interface of the dental structure through at least one air nozzle movably coupled to an intra-oral track; coating the dental structure with a substance to enhance the image quality; and capturing one or more images of the dental structure through at least one image aperture, the image aperture movably coupled to the intra-oral track.

FIELD OF INVENTION

The present invention relates to intra-oral methods and apparatus foroptically imaging a dental structure and creating representative 3Dmodels from the images.

BACKGROUND

In many dental applications, a working model of a patient's teeth isneeded that faithfully reproduces the patient's teeth and other dentalstructures, including the jaw structure. Conventionally, athree-dimensional negative model of the teeth and other dentalstructures is created during an impression-taking session where one ormore U-shaped trays are filled with a dental impression material.Impression materials include, among others, compositions based onalginates, polysulphides, silicones and vulcanizable polyethermaterials. The impression material is typically prepared by mixing abase component and a hardener or initiator or catalyst component. Theimpression tray containing the impression material, in its plasticstate, is introduced into the mouth of the patient. To ensure a completeimpression, an excessive amount of impression material is typicallyused. While the tray and impression material is held in place, thematerial cures, and after curing, the tray and material are removed fromthe mouth as a unit. The impression material is allowed to solidify andform an elastic composition, which is the negative mold after removal.The working model is obtained by filling this impression with a modelingmaterial.

Dental patients typically experience discomfort when the dentist takesan impression of the patient's teeth. The procedure can be even moreuncomfortable for the patient if the impression materials run, slump orare otherwise expelled into the patient's throat. Such situations canpotentially cause a gag reflex reaction from the patient. In addition topatient discomfort, the impression process is time consuming.Additionally, the impression process can be error-prone. For example,when the impression material is not properly applied, the resultingworking model may not accurately reflect features on the teeth.Moreover, the model can show air bubbles trapped during the impressiontaking session. Depending on the accuracy required, such working modelmay not be usable and additional dental impressions may need to betaken. Further, the mold and working model are fragile and can be easilydamaged. The need to store the fragile models for future reference tendsto become a logistical problem for a dental practice as the number ofarchived models accumulates.

Automated scanning techniques have been developed as alternatives to themold casting procedure. Because these techniques can create a digitalrepresentation of the teeth, they provide the advantage of creating an“impression” that is immediately transmittable from the patient to adental laboratory. The digital transmission potentially diminishesinconvenience for the patient and eliminates the risk of damage to themold. For example, U.S. Pat. No. 6,050,821 discloses a method andapparatus for intra-orally mapping the structure and topography ofdental formations such as peridontium and teeth, both intact andprepared, for diagnosis and dental prosthetics and bridgework by usingan ultrasonic scanning technique. As claimed therein, the method canprovide details of orally situated dental formations thus enablingdiagnosis and the preparation of precision moldings and fabricationsthat will provide greater comfort and longer wear to the dental patient.Also, as discussed therein, infra-red CAD/CAM techniques have been usedto map impressions of oral structures and make single-tooth prosthetics.

Also, in certain applications such as restorative dentistry that ispreformed on visible teeth, such as incisors, aesthetic considerationsrequire that the prosthetic interface with the original tooth surface beunderneath the gum (sub gingival) to eliminate the sight of the “joiningline”. In preparation for the prosthetic, the patient's tooth must beshaped to create a ledge or margin beneath the gum line where theprosthetic will be sealed to the existing tooth. To prepare thissurface, the dentist typically places a retraction cord between thetooth and gum. The retraction cord creates a working space that allowsthe dentist to machine the margin around the tooth of interest.

In order for the finished prosthetic to be correctly sized and properlyseated on the prepared tooth, it is essential that the impression of theprepared tooth contain an accurate representation of the sub gingivalmargin. Improper resolution of the margin in the impression and thesubsequent creation of the prosthetic from this impression can result ina poor seal along the margin of the prepared tooth and the prosthetic. Apoor seal along the margin has the potential to expose the underlyingtooth to decay and the subsequent loss of the tooth—the very thing theprosthetic was suppose to prevent. Two methods are commonly used toaccurately capture the margin during the impression process. The firstmethod uses a retraction cord to hold the gum away from the toothsurface to allow the impression compound to flow underneath into the subgingival region. The second method uses an impression material with lowviscosity that under pressure is forced underneath the gums and thuscaptures the sub gingival margin.

In addition to obtaining sub gingival access for the impressionmaterial, the area of interest should be dry and clean (dry field) toobtain an accurate impression. A dry field is needed because typicalimpression compounds are hydrophobic and the presence of moisture whenusing a hydrophobic impression compound results in bubbles in theimpression. The dry field is typically created by the dentist directingpressurized air across the prepared surface just prior to placing theimpression tray in the patient's mouth.

SUMMARY

In one aspect, a method optically images a dental structure within anoral cavity by: directing air at a tooth-gum interface of the dentalstructure through at least one air nozzle movably coupled to anintra-oral track; and capturing one or more images of the dentalstructure through at least one image aperture, the image aperturemovably coupled to the intra-oral track.

Implementations of the above aspect may include one or more of thefollowing. The air nozzle can be moved incrementally or continuouslywithin the oral cavity. A motor may move the air nozzle incrementally orcontinuously within the oral cavity. The dental structure can be coatedwith a substance to enhance the image quality. An illuminator movablymounted on the intra-oral track can illuminate the dental structure. Theilluminator can be moved incrementally or continuously within the oralcavity. A three-dimensional (3D) model of the dental structure can begenerated based on the images captured by the image aperture. Astereometric analysis can be performed on the captured images. Themethod includes performing a scanning illumination beam andtriangulation analysis on the captured images. The 3D model may betransmitted over a network. Diagnosis and treatment of a patient can bedone with the 3D model.

In another aspect, a system to optically image a dental structure withinan oral cavity includes: an intra-oral track adapted to be insertedinside the oral cavity; a pressurized air nozzle moveably coupled to thetrack to direct air at the dental structure; and at least one imageaperture movably coupled to the intra-oral track and adapted to captureone or more images of the dental structure.

Implementations of the above aspect may include one or more of thefollowing. The image aperture is either incrementally or continuouslymoved on the track. A motor coupled to the image aperture can move theimage aperture incrementally or continuously within the oral cavity. Theintra-oral track can be arch-shaped. One or more illuminators movablymounted on the intra-oral track can illuminate the dental structure.Each illuminator is incrementally or continuously moved within the oralcavity. An image processor can perform a stereometric analysis on thecaptured images to generate a three-dimensional model. The imageprocessor can scan an illumination beam and perform triangulationanalysis on the captured images to generate a three-dimensional model. Adisplay can be coupled to the image processor to show a representationof the 3D model. The image processor can be coupled to a network totransmit the 3D model to a remote system. A camera can be connected tothe image aperture, and can be intra-orally mounted or can be mountedoutside of the oral cavity.

In another aspect, a system to optically image a dental structure withinan oral cavity includes an intra-oral track adapted to be insertedinside the oral cavity; a spray orifice moveably coupled to the track tocoat the dental structure with a material; and at least one imageaperture movably coupled to the intra-oral track and adapted to captureone or more images of the dental structure.

In yet another aspect, a system to optically image a dental structurewithin an oral cavity includes an intra-oral track adapted to beinserted inside the oral cavity; a pressurized air nozzle moveablycoupled to the track to direct air at the dental structure; a sprayorifice moveably coupled to the track to coat the dental structure witha material; and at least one image aperture movably coupled to theintra-oral track and adapted to capture one or more images of the dentalstructure.

In still another aspect, a method for optically imaging a dentalstructure within an oral cavity includes coating the dental structurewith a substance to enhance the image quality; and capturing one or moreimages of the dental structure through at least one image aperture, theimage aperture movably coupled to the intra-oral track.

In another aspect, a method for optically imaging a dental structurewithin an oral cavity includes directing air at a tooth-gum interface ofthe dental structure through at least one air nozzle movably coupled toan intra-oral track; coating the dental structure with a substance toenhance the image quality; and capturing one or more images of thedental structure through at least one image aperture, the image aperturemovably coupled to the intra-oral track.

Advantages of the system may include one or more of the following. Thesystem rapidly takes intra oral images of dry field sub gingival dentalstructures. The system also provides a spray orifice to coat dentalstructure with substance to improve the imaging capability. Images ofthe dental structures are captured with sufficient resolution such thatthe acquired images can be processed into accurate 3D models of theimaged dental structures. The images and models would have applicationin dental diagnosis and for the specification and manufacture of dentalprosthetics such as bridgeworks, crowns or other precision moldings andfabrications.

Further, the system provides automated intra-oral scanning of all thedental structures in the jaw through an optical aperture and combinesthe information available in the entire set of images to create andpresent an accurate 3D model of the scanned structures. The systemallows intra-oral images of dental structures to be taken rapidly andwith high resolution such that the acquired images can be processed intoaccurate 3D models of the imaged dental structures. The images andmodels can be used in dental diagnosis and used for the specificationand manufacture of dental prosthetics such as bridgeworks, crowns orother precision moldings and fabrications. In addition, the systemproduces 3D models useful in the diagnosis and treatment planningprocess for dental malocclusions. The system-produced data representinga set of dental images and models can be transmitted electronically tosupport activity such as professional consultations or insuranceprovider reviews, and the images and models may be electronicallyarchived for future reference.

The digital 3D model of patient's teeth and other dental structures hasadvantages over a conventional cast physical model due to thefollowing: 1) 3D model efficiently created in a single step withaccuracy meeting or exceeding the conventional multiple step impressiontechnique; 2)reduced storage costs; 3) immediate, labor-free retrievaland archiving; 4) no model breakage; 5) integrates directly intocomputer based analysis tools for diagnosis and treatment planning; 6)digital models backup; 7) e-mails to colleagues, dental specialists,insurance companies; 8) access to information from home, satelliteoffice; 9) effective presentation tool; 10) no mess and dust; and 11) nowasted staff time.

The above and other features and advantages of the present inventionwill be apparent in the following detailed description of the preferredembodiments of the present invention when read in conjunction with theaccompanying drawings in which corresponding parts are identified by thesame reference symbol.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a system for performing intra-oralscanning and for generating 3D models of teeth and other dentalstructures.

FIG. 2 shows an exemplary embodiment of a scanner with one aperture.

FIG. 3 shows a second embodiment of a scanner with a plurality ofapertures.

FIG. 4 illustrates a process in capturing images and generating 3Dmodels from a patient.

FIG. 5 shows an exemplary image processor for generating 3D models.

FIG. 6 shows an exemplary embodiment for modeling surface location andcontour from stereo images.

FIG. 7 shows an exemplary computer for using the 3D models.

FIG. 8 shows a third exemplary embodiment of a scanner with oneaperture, air nozzle and spray orifice.

FIG. 9 shows a fourth embodiment of a scanner with a plurality ofapertures, air nozzles and spray orifices.

FIG. 10 illustrates a process utilizing air jets and spray orificeswhile capturing images and generating 3D models from a patient.

FIG. 11 shows an exemplary image processor for generating 3D models withcontrols for air jets and spray orifices.

DESCRIPTION

Referring to FIG. 1, a system block diagram depicting theinstrumentation used in scanning teeth and other dental structure imagesand in generating 3D models, will facilitate a general understanding andappreciation of the disclosed method and apparatus.

In FIG. 1, an intra-oral scanner 100 is adapted to be placed inside themouth of the patient (intra-oral cavity). The intra-oral scanner 100captures images of various dental structures in the mouth andcommunicates this information with a remote image processor 110. Theremote image processor 110 in turn can communicate with a computer 120and can display images of the dental structures on a display 122connected to the computer 120. Alternatively, functionalities of thecomputer 120 such as data storage and display can be provided directlyby the remote image processor 110 in another embodiment. Images and 3Dmodels derived from the images can be transmitted as digital files toother equipment or locations by the computer 120.

In one implementation, the intra-oral scanner 100 is embedded in anintra-oral structure, such as a mouthpiece 130. An image aperture 132 isprovided to capture images of the dental structures. The image aperture132 can be an objective lens followed by relay lens in the form of alight-transmission cable such as a fiber optic cable to transmit imagesof the dental structures along a pre-selected distance to a camera. Thefiber optic cable transmits light through small filamentary opticalmaterials or fibers. Typically, the fibers include a central core and anouter surrounding cladding along the entire length of the fiber. Thetransmission of light through the fiber is based on the phenomenon oftotal internal reflection. For total internal reflection, the refractiveindex of the core is greater than the refractive index of the cladding.In one embodiment, optical fibers for the transmission of imagescomprised of visible through mid-infrared light can be used.

The output of the image aperture 132 can be provided to one or moresensors for detecting and converting incident light (photons from thelight source reflected off the dental structure surface)—first intoelectronic charge (electrons) and, ultimately into digital bits. In oneimplementation. the output of the image aperture 132 is provided to acamera (not shown), which can be analog or digital. In one embodiment,the camera contains one or more image sensor(s) used to create digitalimages of the dental structure. These sensors can be devices such as acharge-coupled device (CCD) sensor or a complementary metal oxidesemiconductor (CMOS) image sensor. The image sensor can be an array ofindividual photosensitive cells (pixels) whose size determines thelimiting resolution. Image sensor arrays can have from 16×16 pixels tomore than 1024×1024 pixels, and the arrays can be symmetrical orasymmetrical.

Further, a source of light delivered through an illuminator 134 isprovided to illuminate the dental structures to improve the quality orcontrast of the images taken by the image aperture 132. The light can bewhite light, light shown in one or more colors, or can come from a laserbeam. The intensity of the light source used to illuminate the dentalstructure is ideally controllable and is in the frequency range ofvisible or infra-red light. In one embodiment, the light source can beintegral to the mouthpiece 130. In another embodiment, light can berouted from the light source to the illuminator 134 by one or more fiberoptic cables (not shown). This bundle of optical fibers can bepositioned to surround the outer circumference of the image aperture 132to create a plurality of illuminators. The field of illumination may begreater than the field of view of the image aperture 132 and may rangeup to 180 degrees. In another embodiment, the field of illumination maybe a focused beam that illuminates a spot on the dental structure withan illumination spot size of dimensions less than 5 mm.

A drive mechanism 136 is provided to incrementally or continuously movethe image aperture 132 and the illuminator 134 to various positions inthe intra-oral cavity. In one embodiment, the image aperture 132 and theilluminator 134 are movably mounted on a track that is driven by thedrive mechanism 136. The track can be a U-shaped track conforming to theshape of the patient's arch. The drive mechanism 136 can be electricallyactuated to move the image aperture 132 and the illuminator 134 aroundall teeth and other structures in the jaw. Any of a variety of drivemotors can be used, and the power of the motor through the drivemechanism 136 can be translated into motion for the image aperture 132and the illuminator 134 through rotary, linear, hydraulic, or pneumaticmechanisms for example.

The intra-oral apparatus, as exemplified by mouthpiece 130, provides themechanism for traversing image aperture 132 and the illuminator 134around the oral cavity and positioning the image gathering aperture(s)132A and illuminator(s) 134 at known positions while taking images ofthe dental structures. The mouthpiece 130 in one embodiment includes asensor arc track 210 that allows the image aperture to traverse an arcto capture the image of the dental structure while also moving laterally(FIG. 2). In another embodiment, the mouthpiece 130 supports multipleimage gathering apertures in known mechanical alignment and moving ofsaid apertures laterally around the oral cavity (FIG. 3).

Although the scanning of one jaw arch at a time has been described, itis to be understood that two mouthpieces can be simultaneously deployedto capture images of dental structures on both the upper and lower jawarches.

FIG. 2 shows one embodiment of the mouthpiece having a single imageaperture. In the embodiment of FIG. 2, the mouthpiece 130 has a base 200that is shaped substantially in an arch-shape or U-shape. Mounted on thebase 200 is a lateral rail or track 202 that also conforms to the archshape or U-shape. The track 202 supports a movable shuttle 204 driven bythe drive mechanism 136. The shuttle 204 has an upwardly extending arm206. Resting on top of the arm 206 are the image aperture 132 and theilluminator 134 of FIG. 1. Additionally, the arc track 210 allows thearm 206 to move from a frontal to a posterior view of the teeth. At eachlateral position, the image aperture 132 traverses the arc track 210over the dental structure to collect a sufficient number of images onboth sides of the dental structure before moving to the next lateralposition and repeating the process. The track 202 also includes sensorsor indicators such as scale marks located at either end of the track 202and along the track to provide image aperture positional feedbackinformation. Alternatively, positional information can be ascertained bymethods such as counting drive motor revolutions and deducing theposition based on counting motor revolutions.

FIG. 3 shows another embodiment with multiple image apertures thatrequire only lateral motion. In this embodiment a plurality of imageapertures 132A and the illuminator(s) 134A are mounted in a knownorientation to one another on a laterally moveable apparatus. The numberof image apertures and their orientation is selected to providesufficient coverage and overlap of the dental structure to be modeled atthe desired resolution. At each lateral position, an image from each ofthe apertures 132A is recorded for later processing. In eitherembodiment of FIG. 2 or FIG. 3, the image apertures 132 or 132A may besensors integral to the mouthpiece or fiber optic image bundlesconnected directly to the mouthpiece. In the latter case, the fiberoptic image bundle transmits the image to the image sensor on anexternal printed circuit board (PCB). To optimize the image collectionat the image aperture, mirrored surfaces and optical lenses may beemployed to direct and focus the image onto the image sensor.

As discussed above, the intra-oral scanner 100 contains components thatsupport one or more of the following functions: 1) illuminate the dentalstructure to be imaged; 2) digitally image a dental structure fromdifferent aspects; and 3) reposition both the illumination and imagingapertures so as to traverse the entire intraoral cavity.

The intra-oral scanner 100 can be self-powered or power can be providedby the image processor 110. Further, the output of the intra-oralscanner 100 is received and processed by the image processor 110. In oneembodiment, the output of the scanner 100 includes images transmittedthrough a fiber optic cable. These images are provided to a camera thatdigitizes the images and stores the digital images in a memory buffer.In a second embodiment, the output of the scanner 100 is already indigital form, and this data is stored in the memory buffer of the imageprocessor 110 for processing, as described in more detail below.

FIG. 4 shows an exemplary process 250 for scanning and generating 3Dmodels of dental structures. First, the mouthpiece 130 is inserted intothe patient's mouth (step 252). Next, a reset operation is performed tomove the shuttle 204 to an initial known position (step 254). Theilluminator 134 position, light spectrum and light strength isestablished (step 255). The image processor 110 receives an imagethrough the image aperture 132 and captures the image to its memory(step 256). The image processor 110 then instructs the image aperture132 to traverse the arc track 210 over the dental structure to collect asufficient number of images on both sides of the dental structure (step258). The image processor 110 then actuates the drive mechanism 136 tomove the shuttle 204 to the next incremental lateral position (step260). At each lateral position, the image aperture 132 traverses the arctrack 210 over the dental structure to collect a sufficient number ofimages on both sides of the dental structure before moving to the nextlateral position. Next, the process 250 tests whether the shuttle 204reaches the end of the patient's arch (step 262). If not, the processloops back to step 256 to continue the image acquisition operation. Ifthe end has been reached, the process 250 generates a 3D model using thecaptured images (step 264) and displays the 3D model for review (step266).

Turning now to FIG. 5, an exemplary image processor 110 is shown. Theimage processor 110 includes a central processing unit (CPU) 300, whichcan be a high performance CISC or RISC processor. The CPU 300 isconnected to random access memory (RAM) 302 and read only memory (ROM)304. The CPU 300 also is connected to a plurality of input/outputdevices, including a display 306, a motor and iluminator input/outputport 308 to control the drive mechanism 136 and the illuminator 134(FIG. 1), an image interface 310 to receive image data from the scanner100, and a computer interface 312. The CPU 300 can also be connected toa storage drive 314 such as a hard drive to store software and data andprovides an interface for the communication of data with otherequipment.

The CPU 300 executes code to control the image data acquisition andgenerate 3D models from the captured images. The captured images areprocessed with a pattern recognizer that maps various points of anobject observed in the captured images, thereby obtaining theshape/contour information. In one implementation, 2D digitized images ofthe dental structures are output from the scanner 100 and stored incomputer memory of the image processor 110 along with the positionalinformation and illuminator settings. The stored images from a pluralityof images obtained at different positions of the image aperture are thenanalyzed using stereometric methods to form a 3D view. This process isrepeated for the complete set of captured images to create a full 3Dmodel of the scanned dental structures in the oral cavity. The 3D modelis then presented on a display or used in conjunction with a CAD/CAMsystem for patient diagnosis and treatment.

FIG. 6 shows an exemplary embodiment for using stereo images to modelthe surface contour of dental structures. The example of FIG. 6 isdescribed in terms of two-dimensions, but the process is readilyextended to the third axis to derive three-dimensional surface contoursfor 3D models. With reference to FIG. 6, the following process is usedto derive the position of a specific scene element 480 observed inimages 482 and 484 captured through image apertures 486 and 488.

The image processor uses conventional image pattern matching techniquesto identify a scene element that is observed in both image 482 and image484. Further, based upon the image aperture field of view angle and thelocation of the specific scene element within the image sensor's arrayof pixels, the line of sight angle between the geometric plane of theimage sensor and the scene element is derived. These line of sightangles are denoted in FIG. 6 as Q1 for an image aperture located at X1,Y1 and Q2 for an image aperture located at X2, Y2.

Let the as yet unknown coordinates for the location of the scene elementof interest be denoted x_(u) and y_(u).

Based upon the geometry of the case of FIG. 6,

y _(u)=(tan Q 1•x _(u))+y ₁

and

tan Q 2=−(y _(u) −y ₂)/x _(u)

The value of x_(u) and y_(u) can now be solved using the above twoequations and conventional techniques applicable to sets of linearequations. The stereometric method above can be generalized to add athird dimension Z_(u) and thereby derive a 3D surface contour or modelof the imaged dental structure. The 3D version is based on differencesin the line of sight angles projected into the third dimension to adental structure element as viewed from at least two different aperturelocations.

While for illustrative purposes this description is based upon the useof just two images, it is to be understood that the concept can beextended to more precisely find the 3D coordinates of a scene element byutilizing a multitude of images of the dental structure, taken from amultitude of image aperture positions and utilizing a multitude ofillumination conditions.

In another implementation, image-processing operations based ontriangulation can be used where beams of light are projected onto thedental structures and three-dimensional spatial locations are determinedfor points where the light reflects from the dental structure object. Asthe reflected light bounces off the object at an angle relative to theknown location and bearing of the light source, the system collects thereflection information from a known location relative to the lightsource and then determines the coordinates of the point or points ofreflection by triangulation. A single dot system projects a single beamof light which, when reflected, produces a single dot of reflection. Ascan line system beams a plane of light against the dental structure andwhich is reflected as a curvilinear-shaped set of points describing onecontour line of the object. The location of each point in thatcurvilinear set of points can be determined by triangulation. The systemprojects a light plane (i.e., a laser stripe) from a known location andreads the reflection of multiple points depicting the contour of thedental structure at a location distant from the camera and from whichthe position can be triangulated.

In addition to optical triangulation systems, other alternative opticalscanning systems can be used, including range meters systems. Rangemeter systems typically use an infrared-pulsed laser and mechanicalscanning techniques to project a dot laser across an object and thenmeasure the phase delay of the reflected signal.

Once the dental structure coordinates have been scanned, the systemremoves redundant points and generates a 3D model from the scanned datausing various techniques known in the art. In one embodiment, theprocess examines data for two adjacent laser stripes. Next, the processsweeps through each Y coordinate from the top of the two laser stripesto the bottom of the two stripes and creates triangles for the geometric3D model. When the process has reached the bottom of the stripes, thetriangulating process for the current laser stripes is finished and thenext set of adjacent scan lines are retrieved until a triangulated meshcovering the whole dental structure is generated. Once the mesh has beengenerated, a 3D model with realistic shading and lighting can begenerated.

FIG. 7 shows an exemplary computer 500 for processing dental image dataand for generating 3D models. The system 500 includes a processor (CPU)512, RAM 516, ROM 518 and an I/O controller 520 coupled by a CPU bus514. The I/O controller 520 is also coupled to an I/O bus 535. The I/Obus 535 communicates with an I/O interface 532 that in turn controls asolid state drive (flash RAM) 534 or a removable disk drive. The I/O bus535 is also connected to input devices such as a touch-screen display536. In place of, or in parallel with the touch-screen display 536, akeypad can be connected to the I/O bus 535 to receive user data entry.Alternatively, voice recognition can be used in conjunction with and/orreplace the touch-screen display 536 or keypad. In such an embodiment, amicrophone 537 is connected to an analog to digital converter (ADC) 538that interfaces with the processor 512.

A network access card 540 can be connected to the I/O bus 535 to allowthe computer 500 access to a network 542. Through the network 542, orthrough a modem 550 connected to the I/O bus 535, the computer 500 canaccess a wide area network 560 such as the Internet. An Internetcommunity with one or more service providers or marketers is connectedto the network. The Internet community can provide value added servicessuch as services to create a physical teeth model from the 3D model.

FIGS. 8-9 shows additional embodiments providing additional capabilitiesof directing pressurized air at the dental structure that is beingimaged to 1) create a dry field; and 2) allow sub gingival imagecapture. Furthermore, these embodiments provide a spray orifice fordispensing a coating substance such as titanium dioxide onto the dentalstructures during the digital imaging process. The timing, duration andintensity of the directed air source and spray dispensing on the dentalstructure are precisely controllable. In one implementation, thepressurized air source is obtained by interfacing the apparatus to anexisting air source using an industry standard interface at the patientdental chair.

One embodiment of the mouthpiece uses a single air jet 810 and sprayorifice 820 (FIG. 8). At each lateral position, as the image aperturetraverses an arc over the dental structure, the air jet output isdirected at the region of the dental structure currently being imagedand is synchronized with the image capture. The spray orifice is alsodirected at the dental structure being imaged but dispenses the coatingprior to image capture.

Yet another embodiment uses multiple air jets to simultaneously directair at multiple regions of the dental structure in synchronism with thecapture of the dental structure images (FIG. 9). In this embodiment aplurality of air jets 910 and 910′ are mounted in a known orientation toone another on a laterally moveable apparatus. The number of air jetsand their orientation is selected to provide sufficient coverage andoverlap of the dental structure to be digitally imaged and modeled. Inthe embodiment of FIG. 9, multiple spray orifices 920 and 920′ areintegrated into the mouthpiece to provide coverage of all areas that arebeing imaged. In either embodiment (FIGS. 8 or 9), the pressurized airsource may be integral to the mouthpiece or connected directly to themouthpiece via tubing. In the latter case, the pressurized air source isideally an existing source located at the patient dental chair. Themouthpiece would connect to this source using a standard industryinterface.

In one embodiment, the air nozzle receives air from an air sourcethrough a flexible hose such as a rubber hose. The air supply is passedthrough an air regulator that is in turn connected to an air solenoid toturn on and off the air at appropriate time.

A stream of air is directed at the surface of the dental structure usingthe nozzle. As the air is directed in a thin low pressure stream ontothe dental structure, the particles may be dislodged from the surface ofthe dental structure while the dental structure is dried. The air flowor stream is preferably directed at the dental structure in asubstantially fan-shaped or conical flow pattern so that air strikes thestructure at a range of angles up to about 45 degrees with respect tothe surface of the tooth. This conical flow pattern is elliptical incross-section with a length as much as two to three times its width.

In another embodiment for spraying materials such as whiteningingredients to the dental structure, air supplied by a compressor isdelivered to a chamber in the nozzle. The compressed air in the chambercreates suction on a material line, which runs from the chamber to atank containing the whitening material. The suction draws whiteners fromthe tank into the chamber and entrains the material with the compressedair for delivery onto the dental structure.

FIG. 10 shows an exemplary process 1250 utilizing an air nozzle andspray nozzle for scanning and generating 3D models of dental structures.First, the mouthpiece 130 is inserted into the patient's mouth (step1252). Next, a reset operation is performed to move the shuttle 204 toan initial known position (step 1254). The illuminator 134 position,light spectrum and light strength are established (step 1256). The airnozzle 810 position and air flow characteristic are established (step1258). The coating material spray nozzle 820 position and sprayparameters are established (step 1260). The image processor 110 receivesan image through the image aperture 132 and captures the image to itsmemory (step 1262). The image processor 110 then instructs the imageaperture 132 to traverse the arc track 210 over the dental structure tocollect a sufficient number of images on both sides of the dentalstructure (step 1264). The image processor 110 then actuates the drivemechanism 136 to move the shuttle 204 to the next incremental lateralposition (step 1266). At each lateral position, the image aperture 132traverses the arc track 210 over the dental structure to collect asufficient number of images on both sides of the dental structure beforemoving to the next lateral position. Next, the process 1250 testswhether the shuttle 204 reaches the end of the patient's arch (step1268). If not, the process loops back to step 1262 to continue the imageacquisition operation. If the end has been reached, the process 1250generates a 3D model using the captured images (step 1270) and displaysthe 3D model for review (step 1272).

Turning now to FIG. 11, an embodiment of an image processor 110 thatincludes control of an air nozzle and spray nozzle is shown. The imageprocessor 110 includes a central processing unit (CPU) 1300, which canbe a high performance CISC or RISC processor. The CPU 1300 is connectedto random access memory (RAM) 1302 and read only memory (ROM) 1304. TheCPU 1300 also is connected to a plurality of input/output devices,including a display 1306, a motor and illuminator input/output port 1308to control the drive mechanism 136 and the illuminator 134 (FIG. 1), anair nozzle I/O port 1310 to control the position and operation of theair nozzle 810 (FIG. 8), a spray nozzle I/O port 1312 to control theposition and operation of the material spray nozzle 820 (FIG. 8), animage interface 1314 to receive image data from the scanner 100, and acomputer interface 1316. The CPU 1300 can also be connected to a storagedrive 1318 such as a hard drive to store software and data and providesan interface for the communication of data with other equipment.

The above system supports a rapid imaging of dental structures in such away, and with sufficient resolution such that the acquired images can beprocessed into accurate 3D models of the imaged dental structures. Theimages and models can be processed on the computer 500 to provide dentaldiagnosis and to support the specification and manufacture of dentalprosthetics such as bridgeworks, crowns or other precision moldings andfabrications. The computer 500 can transmit data representing a set ofdental images and models over a wide area network such as the Internetto support activity such as professional consults or insurance providerreviews and the images and models may be electronically archived forfuture reference.

Although an illustrative embodiment of the present invention, andvarious modifications thereof, have been described in detail herein withreference to the accompanying drawings, it is to be understood that theinvention is not limited to this precise embodiment and the describedmodifications, and that various changes and further modifications may beeffected therein by one skilled in the art without departing from thescope or spirit of the invention as defined in the appended claims.

What is claimed is:
 1. A method for optically imaging a dental structurewithin an oral cavity, comprising: a) directing air at a tooth-guminterface of the dental structure through at least one air nozzlemovably coupled to an intra-oral track; and b) capturing one or moreimages of the dental structure through at least one image aperture, theimage aperture movably coupled to the intra-oral track.
 2. The method ofclaim 1, further comprising moving the air nozzle incrementally orcontinuously within the oral cavity.
 3. The method of claim 2, furthercomprising actuating a motor to move the air nozzle incrementally orcontinuously within the oral cavity.
 4. The method of claim 1, furthercomprising coating the dental structure with a substance to enhance theimage quality.
 5. The method of claim 1, further comprising providing anilluminator movably mounted on the intra-oral track to illuminate thedental structure.
 6. The method of claim 5, further comprising movingthe illuminator incrementally or continuously within the oral cavity. 7.The method of claim 1, further comprising generating a three-dimensional(3D) model of the dental structure based on the images captured by theimage aperture.
 8. The method of claim 7, wherein generating athree-dimensional model further comprises performing a stereometricanalysis on the captured images.
 9. The method of claim 7, whereingenerating a three-dimensional model further comprises performing ascanning illumination beam and triangulation analysis on the capturedimages.
 10. The method of claim 7, further comprising transmitting the3D model over a network.
 11. The method of claim 7, further comprisingdiagnosis and treatment of a patient using the 3D model.
 12. A system tooptically image a dental structure within an oral cavity, comprising: anintra-oral track adapted to be inserted inside the oral cavity; apressurized air nozzle moveably coupled to the track to direct air atthe dental structure; and at least one image aperture movably coupled tothe intra-oral track and adapted to capture one or more images of thedental structure.
 13. The system of claim 12, wherein the image apertureis either incrementally or continuously moved on the track.
 14. Thesystem of claim 12, further comprising a motor coupled to the imageaperture to move the image aperture incrementally or continuously withinthe oral cavity.
 15. The system of claim 12, wherein the intra-oraltrack is arch-shaped.
 16. The system of claim 12, further comprising oneor more illuminators movably mounted on the intra-oral track toilluminate the dental structure.
 17. The system of claim 16, whereineach illuminator is incrementally or continuously moved within the oralcavity.
 18. The system of claim 12, further comprising an imageprocessor performing a stereometric analysis on the captured images togenerate a three-dimensional model.
 19. The system of claim 18, whereinthe image processor scans an illumination beam and performstriangulation analysis on the captured images to generate athree-dimensional model.
 20. The system of claim 18, further comprisinga display coupled to the image processor to show a representation ofsaid 3D model.
 21. The system of claim 18, wherein the image processoris coupled to a network to transmit the 3D model to a remote system. 22.The system of claim 12, further comprising a camera coupled to the imageaperture.
 23. The system of claim 22, wherein the camera is intra-orallymounted.
 24. The system of claim 22, wherein the camera is mountedoutside of the oral cavity.
 25. A system to optically image a dentalstructure within an oral cavity, comprising: an intra-oral track adaptedto be inserted inside the oral cavity; a spray orifice moveably coupledto the track to coat the dental structure with a material; and at leastone image aperture movably coupled to the intra-oral track and adaptedto capture one or more images of the dental structure.
 26. A system tooptically image a dental structure within an oral cavity, comprising: anintra-oral track adapted to be inserted inside the oral cavity; apressurized air nozzle moveably coupled to the track to direct air atthe dental structure; a spray orifice moveably coupled to the track tocoat the dental structure with a material; and at least one imageaperture movably coupled to the intra-oral track and adapted to captureone or more images of the dental structure.
 27. A method for opticallyimaging a dental structure within an oral cavity, comprising: a) coatingthe dental structure with a substance to enhance the image quality; andb) capturing one or more images of the dental structure through at leastone image aperture, the image aperture movably coupled to an intra-oraltrack.
 28. A method for optically imaging a dental structure within anoral cavity, comprising: a) directing air at a tooth-gum interface ofthe dental structure through at least one air nozzle movably coupled toan intra-oral track; b) coating the dental structure with a substance toenhance the image quality; and c) capturing one or more images of thedental structure through at least one image aperture, the image aperturemovably coupled to the intra-oral track.